Integrated circuit device packaging structure and packaging method

ABSTRACT

A packaging structure suitable for an integrated circuit device receiving short-wavelength laser light is provided. A lead-mounted substrate is placed on the side of the light receiving surface of the integrated circuit device having a photo detecting part. The lead is electrically connected with the integrated circuit device via an electrode. The integrated circuit device and the substrate are encapsulated with an encapsulation section. The substrate has an opening at a position above the photo detecting part.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a packaging structure of anintegrated circuit device having a photo detecting part, such as anamplifier-embedded light receiving device for an optical disk unit.

[0002]FIG. 7 is a block diagram of an optical disk unit having a laserunit (LDU) shown in terms of functions. Referring to FIG. 7, the laserunit includes a laser device 52 and an integrated circuit device 53having a photo detecting part (optoelectronic integrated circuit(OEIC)). Laser light is emitted from the laser device 52 toward anoptical disk 51, and reflected light from the optical disk 51 isreceived by the photo detecting part of the integrated circuit device53.

[0003] For improvement of the recording density of an optical disk, thebeam diameter of laser light for irradiation of the optical disk hasbeen narrowed. For attaining a narrower beam diameter, the wavelength oflaser light has been gradually made shorter. For example, while thelaser wavelength was 780 nm for CDs, it is 650 nm for DVDs. Fornext-generation DVDs, a further short laser wavelength is used forhigher density.

[0004] The inventors of the present invention set out prototypefabrication and experiments using short-wavelength blue laser, and inthis relation, the following problem was found. That is, a transparentresin was used for encapsulation of a device, as used for conventionalOEICs for DVDs. In this case, however, the transparent resin was partlydeformed/degraded when it was irradiated with short-wavelength bluelaser light.

[0005] The above problem did not occur in the conventional OEICs forDVDs. The cause for this problem has not yet been clarified, butpresumed pertinent to this problem as one factor is that with theshortened wavelength of the laser light, the energy of the laser lightincreases from the conventional level, causing generation of heat fromthe light absorbed into the resin.

SUMMARY OF THE INVENTION

[0006] An object of the present invention is providing a packagingstructure suitable for an integrated circuit device receivingshort-wavelength laser light, and a packaging method for the integratedcircuit device.

[0007] Specifically, the packaging structure of an integrated circuitdevice of the present invention includes: an integrated circuit devicehaving a photo detecting part; a substrate placed on the photo detectingpart side of the integrated circuit device, the substrate being providedwith at least one lead, at least one of the lead being electricallyconnected with the integrated circuit device via an electrode; and anencapsulation section for encapsulating the integrated circuit deviceand the substrate, wherein the substrate has an opening formed above thephoto detecting part.

[0008] The substrate is preferably provided with a bypass capacitor.

[0009] The bypass capacitor is preferably formed on a surface of thesubstrate. Alternatively, the bypass capacitor is preferably formed in asurface portion of the substrate. The bypass capacitor is preferablyformed to be in contact with two leads for which bypassing is performed.

[0010] In the packaging structure of the present invention, an opticalcomponent is preferably placed in the opening of the substrate.

[0011] The optical component is preferably a hologram device, awavelength selective filter or a lens. The optical component ispreferably secured in the opening of the substrate with a screwstructure. Alternatively, the optical component is preferably secured inthe opening of the substrate with a bonding member.

[0012] In the packaging structure of the present invention, the openingof the substrate is preferably provided with a shutter that can beopened/closed and blocks light incident on the photo detecting part inits closed state. The shutter is preferably formed of a liquid crystalmaterial.

[0013] In the packaging structure of the present invention, theintegrated circuit device preferably has a light emitting part on theside of its light receiving surface. The light emitting part ispreferably a laser device.

[0014] The substrate preferably has a second opening formed above thelight emitting part. The second opening is preferably provided with ashutter that can be opened/closed and blocks light emitted from thelight emitting part in its closed state. The shutter is preferablyformed of a liquid crystal material.

[0015] In the packaging structure of the present invention, at leastpart of the back surface of the integrated circuit device is preferablyexposed from the encapsulation section.

[0016] In the packaging structure of the present invention, a heatdissipating member is preferably placed on the back surface side of theintegrated circuit device to be in contact with the integrated circuitdevice and is encapsulated with the encapsulation section together withthe integrated circuit device. At least part of the heat dissipatingmember is preferably exposed from the encapsulation section.

[0017] In the packaging structure of the present invention, a secondintegrated circuit device is preferably placed on the back surface sideof the integrated circuit device to be integral with the integratedcircuit device and is encapsulated with the encapsulation sectiontogether with the integrated circuit device. Preferably, a heatdissipating member is interposed between the integrated circuit deviceand the second integrated circuit device, and at least part of the heatdissipating member is exposed from the encapsulation section.

[0018] In the packaging structure of the present invention, preferably,a hollow defined by the encapsulation section as a side wall is formedbetween the substrate and the integrated circuit, and the encapsulationsection has a through hole formed to allow the hollow to communicatewith the outside of the packaging structure. The axis of the throughhole is preferably approximately parallel to the movement direction of apickup when the packaging structure is used as the pickup.

[0019] In the packaging structure of the present invention, at leastpart of the surface of the substrate on the side of the integratedcircuit device is preferably subjected to antireflection treatment.Antireflection coating is preferably performed as the antireflectiontreatment. Alternatively, satin finish is preferably performed as theantireflection treatment.

[0020] The packaging method for an integrated circuit device of thepresent invention includes the steps of: (1) forming an integratedcircuit device having a photo detecting part; (2) forming a substratehaving at least one lead and an opening; (3) placing the substrate onthe photo detecting part side of the integrated circuit device so thatthe opening is located above the photo detecting part, and electricallyconnecting the integrated circuit device with at least one of the leadof the substrate via an electrode; and (4) encapsulating the substrateand the integrated circuit device, wherein in the step (1), the positionof the electrode is determined based on positional relationships betweenthe photo detecting part and the electrode standardized for a pluralityof types of integrated circuit devices.

[0021] Alternatively, the packaging structure of an integrated circuitdevice of the present invention includes: an integrated circuit device;a substrate placed on the principal surface side of the integratedcircuit device, the substrate being provided with at least one lead, atleast one of the lead being electrically connected with the integratedcircuit device via an electrode; and an encapsulation section forencapsulating the integrated circuit device and the substrate, whereinthe substrate is provided with a bypass capacitor.

[0022] The bypass capacitor is preferably formed on a surface of thesubstrate. Alternatively, the bypass capacitor is preferably formed in asurface portion of the substrate. The bypass capacitor is preferablyformed to be in contact with two leads for which bypassing is performed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is a cross-sectional view of an integrated circuit devicepackaging structure of Embodiment 1 of the present invention.

[0024]FIG. 2 is a plan view of the integrated circuit device packagingstructure of Embodiment 1 of the present invention.

[0025]FIGS. 3A and 3B are a packaged example of the packaging structureof Embodiment 1 of the present invention.

[0026]FIGS. 4A to 4C show alternative examples of placement of a bypasscapacitor.

[0027]FIG. 5 is a cross-sectional view of an integrated circuit devicepackaging structure of Embodiment 2 of the present invention.

[0028]FIGS. 6A to 6C show alternative examples of placement of opticalcomponents.

[0029]FIG. 7 is a block diagram of an optical disk unit having a laserunit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, preferred embodiments of the present invention willbe described with reference to the accompanying drawings.

[0031] Embodiment 1

[0032]FIG. 1 is a cross-sectional view of an integrated circuit devicepackaging structure of Embodiment 1 of the present invention. Referringto FIG. 1, the packaging structure includes an integrated circuit device1 having a photo detecting part 11, such as a photo detector and a photodiode, on the side of its light receiving surface, a substrate 2 placedon the side of the light receiving surface of the integrated circuitdevice 1, and an encapsulation section 5 formed of resin, for example,for encapsulating the integrated circuit device 1 and the substrate 2.Leads 3 are placed to extend through the substrate 2 and electricallyconnected with the integrated circuit device 1 via electrodes 4. Thesubstrate 2 has an opening 6 at a position above the photo detectingpart 11.

[0033] By adopting the structure shown in FIG. 1, the problem that theresin for encapsulation is partly deformed/degraded when irradiated withlight can be avoided. This structure also provides advantages that thepart of the integrated circuit device 1 other than the photo detectingpart 11 is protected with the substrate 2, and that no stray light isgenerated due to existence of a wire because no wire is used forconnection between the integrated circuit device 1 and the substrate 2.

[0034] As used herein, the “lead” refers to a component having a role ofelectrical conduction from an electrode of the integrated circuit deviceto an external terminal. The lead also has roles of dissipating heat andprotecting the integrated circuit device from the external environment(for example, the lead absorbs external vibration to protect theintegrated circuit device from influence of the vibration).

[0035] A bypass capacitor 21 is placed on the substrate 2 for improvingthe characteristics of any electronic circuit constituting theintegrated circuit device 1 other than the photo detecting part 11. Theeffect of improving an electronic circuit is greater as the distancebetween the bypass capacitor 21 and the electronic circuit is shorter.In the structure shown in FIG. 1, in which the bypass capacitor 21 isformed on the surface of the substrate 2, it is possible to place thebypass capacitor 21 in the immediate vicinity of a circuit of theintegrated circuit device 1. By embedding the bypass capacitor 21 in thepackaging structure itself, a user intending to incorporate thepackaging structure in a device system does not have to place a bypasscapacitor separately. This simplifies the device system.

[0036] A heat dissipating plate 7 made of metal as the heat dissipatingmember is placed on the side of the back surface of the integratedcircuit device 1 to be in contact with the integrated circuit device 1.The heat dissipating plate 7 is encapsulated with the encapsulationsection 5, together with the integrated circuit device 1, although partthereof is exposed from the encapsulation section 5. The heatdissipating plate 7 not only improves the heat dissipation of thepackaging structure but also serves as a shield.

[0037]FIG. 2 is a plan view of the packaging structure of thisembodiment. In the example shown in FIG. 2, a first bypass capacitor 21a is placed between leads 3 a and 3 b to be used as power supply pins,and a second bypass capacitor 21 b is placed between the lead 3 a and alead 3 c, among the leads 3. The first bypass capacitor 21 a is incontact with the leads 3 a and 3 b for which bypassing is performed, andthe second bypass capacitor 21 b is in contact with the leads 3 a and 3c for which bypassing is performed. Due to the direct contact of thebypass capacitors 21 a and 21 b with the leads 3 a, 3 b and 3 c withoutinterconnections therebetween, the effect of the bypass capacitors 21 aand 21 b of improving the circuit characteristics is exhibited moresignificantly.

[0038] The positions of the electrodes 4 may be determined based on thepositional relationships between the photo detecting part 11 and theelectrodes 4 standardized for a plurality of types of integrated circuitdevices. By determining in this way, the facilities and process can besimplified in fabrication of many types of integrated circuit devices.

[0039]FIGS. 3A and 3B are a cross-sectional view and a plan view,respectively, of a packaged example of the packaging structure of FIGS.1 and 2. In this example, flexible cables 8 a and 8 b are placed atpositions above the substrate 2, and the leads 3 formed through thesubstrate 2 are electrically connected with the flexible cables 8 a and8 b via through holes 9A with solder 9.

[0040] The bypass capacitor may be placed at any of various positionsother than on the substrate 2. FIGS. 4A to 4C show other examples ofplacement of the bypass capacitor. In FIG. 4A, the bypass capacitor 21is interposed between the integrated circuit device 1 and the substrate2. In FIG. 4B, the bypass capacitor 21 is formed in the surface portionof the substrate 2 on the side of the integrated circuit device 1. InFIG. 4C, the bypass capacitor 21 is formed in the surface portion of thesubstrate 1 on the outer side opposite to the integrated circuit device1.

[0041] The opening 6 of the substrate 2 may be provided with a shutterthat can be opened/closed and blocks light from being incident on thephoto detecting part 11 in its closed state. The shutter is preferablycomposed of a liquid crystal material, for example.

[0042] At least part of the surface of the substrate 2 on the side ofthe integrated circuit device 1 may be subjected to antireflectiontreatment, to eliminate generation of reflected stray light from thesubstrate 2. As the antireflection treatment, antireflection coating orsatin finish may be performed.

[0043] At least part of the back surface of the integrated circuitdevice 1 may be exposed from the encapsulation section 5.

[0044] The effect obtained by providing a bypass capacitor for thesubstrate in this embodiment can also be provided for a packagingstructure in which the integrated circuit device has no photo detectingpart and thus the substrate has no opening.

[0045] Embodiment 2

[0046]FIG. 5 is a cross-sectional view of an integrated circuit devicepackaging structure of Embodiment 2 of the present invention. Thestructure of FIG. 5 is based on the structure of FIG. 1 and has some newtechnical features added thereto.

[0047] First, an optical component such as a lens 31, for example, isplaced in an opening 6 of a substrate 2A. In the illustrated example,the lens 31 is secured to the substrate 2A in the opening 6, togetherwith a spacer 32, with a bonding member. As the optical component, ahologram device, a wavelength selective filter or the like may be placedin place of the lens 31. The optical component may be secured to thesubstrate 2A with a screw structure by threading both the opticalcomponent and the face of the substrate 2A exposed to the opening 6.

[0048]FIGS. 6A to 6D show other examples of placement of the opticalcomponent. In FIG. 6A, a lens 31A as the optical component is securedwithout use of a spacer. In FIG. 6B, two lenses 31 a and 31 b aresecured. Likewise, in FIG. 6C, two lenses 31 c and 31 d are secured, andin FIG. 6D, two lenses 31 e and 31 f are secured.

[0049] Secondly, light emitting parts 12 a and 12 b such as laserdevices are placed on the side of the light receiving surface of theintegrated circuit device 1A. Openings 33 a and 33 b for optical pathsare formed through the substrate 2A at positions above the lightemitting parts 12 a and 12 b as the second openings.

[0050] Moreover, another integrated circuit device 34 is placed on theside of the back surface of the integrated circuit device 1A to beintegral with the integrated circuit device 1A. The integrated circuitdevice 34, provided for executing processing of digital signals and thelike, for example, is encapsulated with an encapsulation section 5A,together with the integrated circuit device 1A. A heat dissipating plate35 as the heat dissipating member is interposed between the integratedcircuit device 1A and the integrated circuit device 34. The heatdissipating plate 35 has a portion 35 a exposed from the encapsulationsection 5A. A heat dissipating plate 36 is placed in contact with theintegrated circuit device 34, with the back surface thereof exposed fromthe encapsulation section 5A.

[0051] Furthermore, a hollow 13 defined by the encapsulation section 5Aas the side wall is formed between the substrate 2A and the integratedcircuit device 1A. A through hole 37 is formed through the encapsulationsection 5A to allow the hollow 13 to communicate with the outside of thepackaging structure. The through hole 37 has a function of cooling thehollow 13. When this packaging structure is used as a pickup, the axisof the through hole 37 is desirably roughly parallel to the movementdirection of the pickup.

[0052] Each of the second openings 33 a and 33 b of the substrate 2A maybe provided with a shutter that can be opened/closed and blocks lightemitted from the light emitting part 12 a or 12 b in its closed state.The shutter is preferably composed of a liquid crystal material, forexample.

[0053] As described above, according to the present invention, apractically suitable packaging structure can be provided for anintegrated circuit device receiving short-wavelength laser light.

[0054] While the present invention has been described in preferredembodiments, it will be apparent to those skilled in the art that thedisclosed invention may be modified in numerous ways and may assume manyembodiments other than that specifically set out and described above.Accordingly, it is intended by the appended claims to cover allmodifications of the invention which fall within the true spirit andscope of the invention.

What is claimed is:
 1. A packaging structure of an integrated circuitdevice having a photo detecting part, comprising: a substrate placed onthe photo detecting part side of the integrated circuit device, thesubstrate being provided with at least one lead, at least one of thelead being electrically connected with the integrated circuit device viaan electrode; and an encapsulation section for encapsulating theintegrated circuit device and the substrate, wherein the substrate hasan opening formed above the photo detecting part.
 2. The structure ofclaim 1, wherein the substrate is provided with a bypass capacitor. 3.The structure of claim 2, wherein the bypass capacitor is formed on asurface of the substrate.
 4. The structure of claim 2, wherein thebypass capacitor is formed in a surface portion of the substrate.
 5. Thestructure of claim 2, wherein the bypass capacitor is formed to be incontact with two leads for which bypassing is performed.
 6. Thestructure of claim 1, wherein an optical component is placed in theopening of the substrate.
 7. The structure of claim 6, wherein theoptical component is a hologram device, a wavelength selective filter ora lens.
 8. The structure of claim 6, wherein the optical component issecured in the opening of the substrate with a screw structure.
 9. Thestructure of claim 6, wherein the optical component is secured in theopening of the substrate with a bonding member.
 10. The structure ofclaim 1, wherein the opening of the substrate is provided with a shutterthat can be opened/closed and blocks light incident on the photodetecting part in its closed state.
 11. The structure of claim 10,wherein the shutter is formed of a liquid crystal material.
 12. Thestructure of claim 1, wherein the integrated circuit device has a lightemitting part on the side of its light receiving surface.
 13. Thestructure of claim 12, wherein the light emitting part is a laserdevice.
 14. The structure of claim 12, wherein the substrate has asecond opening formed above the light emitting part.
 15. The structureof claim 14, wherein the second opening is provided with a shutter thatcan be opened/closed and blocks light emitted from the light emittingpart in its closed state.
 16. The structure of claim 15, wherein theshutter is formed of a liquid crystal material.
 17. The structure ofclaim 1, wherein at least part of the back surface of the integratedcircuit device is exposed from the encapsulation section.
 18. Thestructure of claim 1, wherein a heat dissipating member is placed on theback surface side of the integrated circuit device to be in contact withthe integrated circuit device and is encapsulated with the encapsulationsection together with the integrated circuit device.
 19. The structureof claim 18, wherein at least part of the heat dissipating member isexposed from the encapsulation section.
 20. The structure of claim 1,wherein a second integrated circuit device is placed on the back surfaceside of the integrated circuit device to be integral with the integratedcircuit device and is encapsulated with the encapsulation sectiontogether with the integrated circuit device.
 21. The structure of claim20, wherein a heat dissipating member is interposed between theintegrated circuit device and the second integrated circuit device, andat least part of the heat dissipating member is exposed from theencapsulation section.
 22. The structure of claim 1, wherein a hollowdefined by the encapsulation section as a side wall is formed betweenthe substrate and the integrated circuit, and the encapsulation sectionhas a through hole formed to allow the hollow to communicate with theoutside of the packaging structure.
 23. The structure of claim 22,wherein the axis of the through hole is approximately parallel to themovement direction of a pickup when the packaging structure is used asthe pickup.
 24. The structure of claim 1, wherein at least part of thesurface of the substrate on the side of the integrated circuit device issubjected to antireflection treatment.
 25. The structure of claim 24,wherein antireflection coating is performed as the antireflectiontreatment.
 26. The structure of claim 24, wherein satin finish isperformed as the antireflection treatment.
 27. A packaging method for anintegrated circuit device having a photo detecting part, the methodcomprising the steps of (1) forming the integrated circuit device; (2)forming a substrate having at least one lead and an opening; (3) placingthe substrate on the photo detecting part side of the integrated circuitdevice so that the opening is located above the photo detecting part,and electrically connecting the integrated circuit device with at leastone of the lead of the substrate via an electrode; and (4) encapsulatingthe substrate and the integrated circuit device, wherein in the step(1), the position of the electrode is determined based on positionalrelationships between the photo detecting part and the electrodestandardized for a plurality of types of integrated circuit devices. 28.A packaging structure of an integrated circuit device, comprising: asubstrate placed on the principal surface side of the integrated circuitdevice, the substrate being provided with at least one lead, at leastone of the lead being electrically connected with the integrated circuitdevice via an electrode; and an encapsulation section for encapsulatingthe integrated circuit device and the substrate, wherein the substrateis provided with a bypass capacitor.
 29. The structure of claim 28,wherein the bypass capacitor is formed on a surface of the substrate.30. The structure of claim 28, wherein the bypass capacitor is formed ina surface portion of the substrate.
 31. The structure of claim 28,wherein the bypass capacitor is formed to be in contact with two leadsfor which bypassing is performed.